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Old February 5, 2019, 04:46 PM   #1
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Light Strikes with my S&W Revolver

I own a S&W model 19-3 revolver that I reload for. I go as often as I can to the range to test out my recipes. For the last couple of months, I have been getting the occasional misfire due to light strikes on the primer. I am using CCI 500 brand primers. I know they are light strikes because each time, after waiting a half minute, I open the cylinder, rotate 1 position clockwise, close the cylinder, and fire again. Each time the round goes off as expected. This happens maybe once every 100 to 200 rounds.

I would provide pictures but I keep forgetting to save the round that misfired. I remember each showing a less than definite depression in the primer. On the second try, after a successful firing, firing pin depression is much more definite.

Obviously, I will be taking my gun to my gunsmith. What do you think my gunsmith will tell me? Should I be getting a new firing pin? Is it a contamination issue? Is it a wear issue?
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Old February 5, 2019, 04:57 PM   #2
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Most likely I'd guess the strain screw in the grip frame has back out a little, or you aren't seating the primer deep enough on occasion.

Once out of every 200 rounds is pretty infrequent, but often enough to be annoying. Maybe the mainspring was adjusted or swapped out by a previous owner. Have you tried a new one? Federal primers are supposed to be easy to ignite than everything else. You could buy 1,000 of those and see if you get any misfires.

Could also be the strain screw was shortened by a previous owner...
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Old February 5, 2019, 05:33 PM   #3
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Originally Posted by reddog81 View Post
Most likely I'd guess the strain screw in the grip frame has back out a little
Strain screw...of course! Thanks, redog81!
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Old February 5, 2019, 05:34 PM   #4
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I would guess what reddog81 said either mainspring screw is not tight or has been shortened. Also if it only happens every so often, it could be on occasion that you are not seating the primer all the way. I used to have that happen more often than you when I used an old Lyman press that didn't always seat the primer flush. The first strike with the hammer pushes the primer all the way in and the second strike actually fires the primer
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Old February 5, 2019, 05:40 PM   #5
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Originally Posted by Eddietruett View Post
it could be on occasion that you are not seating the primer all the way.
I thought of that, too. Began checking quite a while ago to see if every round had a well-seated primer. Also began making sure I pressed the primer in a little bit harder. Still got an occasional light strike. So I think reddog81 has probably hit on it.

Still a good suggestion though. Thanks. If strain screw adjustment doesn't work, I may switch primers.
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Old February 7, 2019, 11:06 AM   #6
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I just finished a thread on the S&W forum. It was in fact the strain screw. It is a model 25 shooting 45 ACP. Worked fine for several years and then one day nada. I wasn't sure so I screwed it in a turn or so. It was better but not 100%. After getting advice from others I went ahead and screwed it in all the way until snug. That did it, went to the range on Monday and had no fails.
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Old February 7, 2019, 03:41 PM   #7
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People tend to use strain screw to adjust trigger pull. It's suppose to be all the way in. You can buy spring sets for lighter pull but strain screw still goes in all the way. I bought a 19-2, that I still have. It had spring kit in it for light SA trigger pull. Gun shot well and one day it
started opening up the group. Thinking I needed to scrub the barrel I did. Then it started to
misfire from light strikes. I decided it was the aftermarket spring. Put original back in which I got with gun, same thing. Then I found the first 150 rds fired were Win primers. The batch I had been using since problems were CCI. Turn out a lot of guys were having light strike misfires with CCI 500 & 550 primers. Except in SAs they worked fine. The light strikes on those hard primers (550s) was causing UN uniform ignition and opening up groups. I wouldn't have noticed but was shooting rested with scope.
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Old February 7, 2019, 07:32 PM   #8
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As others have suggested, the strain screw is the first thing to check when a S&W revolver has misfires. The strain screw is the most common cause of misfires, and it should always be fully tightened down.

If there is no problem with the strain screw, then there are a variety of other issues that can contribute to misfires. I wrote an article on working with the triggers on S&W revolvers, and the article has a section on the causes of misfires.

The article is here:

Improving the trigger on Smith & Wesson Revolvers

The section on the causes of misfires is here:

Issues which cause light strikes

The article is also discussed in this thread:
My blog:
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firing pin , light strike

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